JP2010218646A - Optical information recording medium and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a write-once super resolution optical information recording medium capable of crystallizing a phase change layer used as a super resolution layer without modifying a recording layer, and to provide a method of manufacturing the write once super resolution optical information recording medium. <P>SOLUTION: The optical information recording medium includes the recording layer 13 on which information is recorded by applying first laser beams having a first wavelength, further includes the phase change layer 17 that is formed between the light source of laser beams and the recording layer 13 and is crystallized by applying second laser beams having a second wavelength, and further includes an intermediate layer 15, where transmittance to the first laser beams is higher than that to the second laser beams between the recording layer 13 and the phase change layer 17. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical information recording medium, and more particularly to a write-once super-resolution optical information recording medium.

  An optical disc is known as an example of an optical information recording medium that reproduces information by laser light irradiation. Optical discs are classified into a read-only type (ROM: Read Only Memory) that only reproduces recorded information, a write-once type that can be recorded only once, and a rewritable type that can rewrite data. Of these, ROM is widely used as a distribution medium for images or package software because it can be mass-replicated at low cost and at high speed by using a technique called injection molding. The write-once and rewritable markets have also expanded, driven by the proliferation of ROMs. In consideration of further progress in image quality improvement in the future, it is desired that the optical disk has a larger capacity.

  The capacity of the optical disc depends on the beam diameter of the laser beam used for reproducing information. The smaller the beam diameter, the higher density information can be reproduced without error. The light emitted from the laser diode is focused through the objective lens, but is not focused at one point due to the influence of diffraction, and a focused spot having a finite size is formed. In general, this is called the diffraction limit. When the wavelength of the laser beam is λ and the numerical aperture of the objective lens is NA, λ / (4NA) is the limit of the reproduction resolution.

  For example, when λ = 405 nm and NA = 0.65, a pit having a length of 156 nm or less cannot be accurately read. In order to accurately read a pit having a length of 156 nm or less, it is necessary to make the wavelength of the laser light shorter than 405 nm or make the numerical aperture of the objective lens larger than 0.65. However, current laser technology has limitations in providing short wavelength lasers. In addition, for light having a wavelength shorter than 405 nm, a polycarbonate substrate generally used for optical disks is not transparent. Furthermore, in order to increase the numerical aperture, a high NA objective lens has a problem of high manufacturing cost. Further, as the numerical aperture of the objective lens increases, the distance between the pickup and the optical disk decreases, so that the optical head and the optical disk collide with each other and the optical disk surface is damaged, thereby increasing the risk of data loss.

  As a countermeasure against this problem, there is known a medium super-resolution technique for improving the reproduction resolution exceeding the diffraction limit as disclosed in Patent Document 1. In the medium super-resolution, a medium using a super-resolution layer whose optical characteristics change nonlinearly depending on temperature or light intensity is used.

  FIG. 6 is a top view of a general optical disc when the phase change layer is used as a super-resolution layer. In FIG. 6, the row of pits 60, which are recording marks, formed in advance on a transparent substrate of a super-resolution optical disk is shown in an enlarged manner. On this optical disk, the laser beam that has passed through the objective lens is irradiated to form a condensing spot 61. Further, the irradiated laser light is absorbed by the phase change layer, and the temperature of the phase change layer rises. Of the region where the temperature has risen, particularly in the melted region that exceeds the melting point of the phase change layer, the reflectivity increases as the phase change layer changes from the solid phase state to the liquid phase state, and the opening 62 reproduces the recording mark. Will function as. As a result, the size of the opening 62 contributing to reproduction can be made smaller than the size of the focused spot 61 determined by the diffraction limit. Therefore, information on a minute recording mark below the diffraction limit can be read as a super-resolution reproduction signal.

  Such a phase change layer can be used as a super-resolution layer not only in a ROM but also in an optical information recording medium such as a write-once optical disk described in Patent Document 2.

JP-A-5-89511 JP 2004-220687 A

  The operation when the above-described phase change layer having the super-resolution function is applied to a write-once optical information recording medium will be described. 7 and 8 are a cross-sectional view (a) of a recording layer showing a recording mark position of a write-once optical information recording medium and a top view of the phase change layer when the phase change layer is used as a super-resolution layer. (B).

  When recording information, the recording mark 74 is formed by irradiating the recording layer 74 shown in FIG. Further, as shown in FIG. 7B, since the phase change layer 70 immediately after film formation is generally in an amorphous state, the phase change layer 70 is in an amorphous state before the start of recording. In a part of the phase change layer 70 where the recording mark 75 is formed where the recording light is irradiated, a crystal region 71 is formed that is heated to a melting point or higher and melted and then crystallized. Further, in the peripheral region of the crystal region 71, although the phase change layer 70 does not melt, a crystal region 72 to be crystallized is formed to raise the temperature to the crystallization temperature or higher. The portion that is not crystallized in the phase change layer 70 remains in an amorphous state and becomes an amorphous region 73.

  When super-resolution reproduction is performed, as shown in FIG. 8B, in the track center portion, after the phase change layer 70 is melted in the melted portion 81 in a range narrower than the crystal region 71 formed at the time of recording. Crystallize. This is because the playback power is lower than the recording power. As a result, in the condensed spot 82 formed by the reproduction beam, four kinds of reflectances of R1 (amorphous), R2 (melted), R3 (crystal after melting), and R4 (crystal without melting) are provided. The areas that it has will be mixed. In order to make it possible to reproduce a finer recording mark, it is necessary to increase the reflectance contrast between the mask (melted portion) and the mask. However, write-once optical discs have many design restrictions such as recording sensitivity and reproduction light resistance, and the thickness of each film cannot be freely changed. For example, R2 is any of R1, R3, and R4. It is difficult to make it bigger. Also, if the reflectances of R1, R3 and R4 are not substantially equal, the difference in reflectance becomes unnecessary noise and is mixed in the signal, so that the S / N (Signal / Noise) of the reproduced signal is lowered. I will let you.

  In order to solve this problem, prior to the start of recording on the recording layer 74, initialization of forming the crystal region 91 by crystallizing the phase change layer 70 over a wide range as shown in FIG. Crystallization (initialization) of the phase change layer can be performed using an initialization apparatus applied to DVD-RAM (Digital Versatile Disk-Random Access Memory), DVD-RW (Digital Versatile Disk-ReWritable), and the like. . The phase change layer can take various crystal states depending on the initialization conditions, but the degree to which the phase change layer melts to be the same as the molten crystal state generated at the center of the focused spot during super-resolution reproduction. It is preferable to perform initialization by irradiating a high-power laser beam.

  However, in the write-once type optical disc as described above, the recording layer also absorbs laser light and deteriorates during initialization. As a result, after initialization, the recording layer is in a recorded state, which causes a problem that data that should be recorded cannot be recorded.

  An object of the present invention is to provide a write-once super-resolution optical information recording medium that can crystallize a phase-change layer used as a super-resolution layer without deteriorating the recording layer, and a method for manufacturing the same. And

  An optical information recording medium of one embodiment of the present invention includes a recording layer on which information is recorded by being irradiated with a first laser beam having a first wavelength, a light source of the laser beam, and the recording layer. A phase change layer that is crystallized by irradiation with a second laser beam having a second wavelength, and is formed between the recording layer and the phase change layer, and the first laser It comprises at least an intermediate layer having a light transmittance higher than that of the second laser light.

  The method for manufacturing an optical information recording medium of one embodiment of the present invention includes a step of forming a recording layer on which information is recorded by irradiation with a first laser beam having a first wavelength, and a second wavelength. A step of forming a phase change layer that is crystallized by irradiation with a second laser beam having a laser beam between the light source of the laser beam and the recording layer, and the transmittance for the first laser beam is And a step of forming an intermediate layer having a higher transmittance than the second laser light between the recording layer and the phase change layer.

  According to the present invention, it is possible to provide a write-once super-resolution optical information recording medium that can crystallize a phase-change layer used as a super-resolution layer without deteriorating the recording layer, and a method for manufacturing the same. Can do.

1 is a cross-sectional view of an optical information recording medium according to a first embodiment. 6 is a cross-sectional view of an optical information recording medium according to Embodiment 2. FIG. 6 is a sectional view of an optical information recording medium according to Example 2. FIG. 7 is a cross-sectional view of an optical information recording medium according to Example 3. FIG. 10 is a cross-sectional view of an optical information recording medium according to Comparative Example 3. FIG. It is a top view of an optical information recording medium. FIG. 2 is a cross-sectional view (a) of a recording layer of an optical information recording medium and a top view (b) of a phase change layer. FIG. 2 is a cross-sectional view (a) of a recording layer of an optical information recording medium and a top view (b) of a phase change layer. FIG. 2 is a cross-sectional view (a) of a recording layer of an optical information recording medium and a top view (b) of a phase change layer.

Embodiment 1
Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view schematically showing the configuration of the optical information recording medium according to the first embodiment. As shown in FIG. 1, the optical information recording medium includes a reflective layer 11 made of an Ag alloy, a dielectric layer 12, a recording layer 13, a dielectric layer 14, and an intermediate layer 15 made of an Ag alloy in this order from the substrate 10 side. A dielectric layer 16, a phase change layer 17, a dielectric layer 18, and a light transmission layer 19 are laminated.

  In this optical information recording medium, in order to crystallize (initialize) the phase change layer 17, for example, when laser light having a wavelength of 810 nm is irradiated as initialization light, the temperature of the phase change layer 17 increases due to light absorption. And then cooled and crystallized.

  Further, the Ag alloy used for the intermediate layer 15 has a low transmittance with respect to, for example, red light (wavelength range of about 650 to 810 nm). Therefore, the initialization light transmitted through the phase change layer 17 is blocked by the intermediate layer 15 and hardly reaches the recording layer 13. Therefore, it is possible to prevent the recording layer 13 from being deteriorated by absorbing the initialization light.

  The phase change layer 17 absorbs the initialization light and generates heat. And that heat diffuses and raises the temperature of other layers. However, since the thermal diffusivity of Ag alloy is sufficiently high, it functions as a heat sink. Therefore, the temperature rise of the recording layer 13 can be suppressed sufficiently low. Therefore, the alteration of the recording layer 13 due to the temperature rise due to thermal diffusion can also be prevented.

  The Ag alloy has a high transmittance for recording / reproducing light having a wavelength of about 405 nm, for example, used for recording / reproducing information. Therefore, since the recording / reproducing light passes through the intermediate layer 15 and reaches the recording layer 13, the intermediate layer 15 does not become an obstacle to recording and reproduction.

  Therefore, according to this configuration, it is possible to realize a write-once super-resolution optical information recording medium that can initialize the phase change layer 17 without deteriorating the recording layer 13.

Example 1
In Example 1, in the optical information recording medium according to the first embodiment, a reflective layer 11 made of AgPdCu having a thickness of 100 nm and a thickness of 20 nm are sequentially formed from the substrate 10 side made of polycarbonate having a thickness of 1.1 mm and a diameter of 120 mm. A dielectric layer 12 made of SiN, a recording layer 13 made of Co ₃ O _{4 with} a thickness of 10 nm, a dielectric layer 14 made of ZnS—SiO _{2 with} a thickness of 30 nm, an intermediate layer 15 made of AgPdCu with a thickness of 10 nm, a thickness A dielectric layer 16 made of ZnS—SiO _{2 with} a thickness of 70 nm, a phase change layer 17 made of Sb ₈₀ Te _{20 with} a thickness of 10 nm, and a dielectric layer 18 made of ZnS—SiO _{2 with} a thickness of 35 nm were laminated by sputtering, and A light transmission layer 19 made of an ultraviolet curable resin having a thickness of 0.1 mm was laminated thereon.

  In addition, a tracking guide groove having a pitch of 0.32 μm and a depth of 20 nm was formed on the substrate 10. (Not shown).

  In this embodiment, laser light having a wavelength of 810 nm was used as initialization light, and laser light having a wavelength of 405 nm was used as recording / reproducing light.

  When the light transmittance of the 10 nm thick AgPdCu film, which is the intermediate layer 15 of this example, was measured, it was about 20% for the initialization light, but for the recording / reproducing light. A higher transmittance of about 60% could be realized.

  In addition, the absorptivity of the initialization light in the recording layer 13 of this example was 1.1% (design value), which is a value low enough to prevent the recording layer 13 from being altered.

  In this optical information recording medium, the phase change layer 17 was crystallized by irradiating the initialization light using an initialization apparatus having an optical head with NA = 0.55. Specifically, in order to shorten the initialization time, the condensing spot diameter of the laser beam mounted on the initialization apparatus was set to about 100 μm. Further, initialization was performed by moving the focused spot in the radial direction by 50 μm per rotation of the disk under the conditions of a linear velocity of 7.5 m / s and an irradiation laser power of 800 mW.

After initialization, the recording / reproducing light is irradiated using an optical head with NA = 0.85, and (1-7) modulated random data is recorded / reproduced under the conditions of a linear velocity of 4.92 m / s and a recording clock frequency of 132 MHz. As a result, a good error rate of 10 ⁻⁵ or less was obtained in the range of 15 mW recording power and 2.7 to 3.3 mW reproducing power.

  Therefore, in Example 1, the phase change layer 17 could be crystallized without the recording layer 13 being altered and being in a recorded state.

  For example, in an optical information recording medium having no intermediate layer, the recording layer absorptance with respect to initialization light can be increased by optimizing the material selection and thickness of the dielectric layer and phase change layer. There is a possibility that it can be made to the same extent as this embodiment. However, it is difficult to ensure good recording / reproducing characteristics by recording / reproducing light with this restriction.

  On the other hand, if the intermediate layer as used in this embodiment is provided, the absorptivity of the initialization light in the recording layer is inevitably reduced. Therefore, the thickness of each layer may be optimized by paying attention only to the recording / reproducing characteristics using the recording / reproducing light, and a write-once super-resolution optical information recording medium can be obtained easily.

Comparative Example 1
Using an optical information recording medium having the same configuration as in Example 1, information was recorded and reproduced without initializing the phase change layer 17. The linear velocity and recording clock frequency during recording were the same as those in Example 1. In this comparative example, since the phase change layer 17 was not initialized, the phase change layer 17 at the start of recording was in an amorphous state, and the recording power was 14 mW, which was slightly lower than that of Example 1. Further, although the reproduction power was changed variously, an error rate of 10 ⁻³ or less could not be obtained. This is considered to be caused by the fact that amorphous regions and crystal regions are mixed in the condensing spot of the recording / reproducing light and the S / N is lowered.

  Therefore, it was confirmed that the error rate can be reduced and the S / N during reproduction can be improved by initializing the phase change layer 17.

Embodiment 2
FIG. 2 is a cross-sectional view schematically showing the configuration of the optical information recording medium according to the second embodiment. As shown in FIG. 2, in this optical information recording medium, a reflective layer 21 made of an Ag alloy, a dielectric layer 22, a recording layer 23, and two types of dielectric layers having different refractive indexes are repeatedly formed from the substrate 20 side. The intermediate layer 25, the phase change layer 27, the dielectric layer 28, and the light transmission layer 29 are stacked.

The light transmittance of the intermediate layer 25 can be increased for recording / reproducing light and decreased for initialization light by optimizing the design of the intermediate layer 25. As described above, the intermediate layer 25 is formed by repeatedly forming two types of dielectric layers having different refractive indexes. Here, the refractive index of one of the dielectric layers n _1, the refractive index of the other dielectric layer and n _2, and n _1> n _2. In order to reduce the transmittance of the intermediate layer 25 with respect to the initialization light by setting the wavelength of the initialization light to λ, the thickness of the respective dielectric layers is set to λ / 4n ₁ and λ / 4n _2. Satisfies the high reflection condition for the initialization light and can prevent the initialization light from being transmitted.

  Therefore, according to this configuration, it is possible to realize a write-once super-resolution optical information recording medium that can initialize the phase change layer 27 without deteriorating the recording layer 23.

Example 2
In Example 2, in the optical information recording medium according to the second embodiment, the intermediate layer is composed of three dielectric layers. FIG. 3 is a cross-sectional view schematically showing the configuration of the optical information recording medium according to the second embodiment. In Example 2, as shown in FIG. 3, the intermediate layer 251 includes a dielectric layer 251a, a dielectric layer 251b, and a dielectric layer 251c. Other configurations are the same as those in FIG.

Specifically, on a substrate 20 made of polycarbonate having a thickness of 1.1 mm and a diameter of 120 mm, a reflective layer 21 made of AgPdCu having a thickness of 100 nm, a dielectric layer 22 made of SiN having a thickness of 20 nm, in order from the substrate 20 side, A recording layer 23 made of Co ₃ O _{4 with} a thickness of 10 nm, an intermediate layer 251 composed of three dielectric layers 251a-c, a phase change layer 27 made of Sb ₈₀ Te _{20 with} a thickness of 10 nm, and a thickness of 50 nm A dielectric layer 28 made of ZnS—SiO ₂ was laminated by sputtering, and a light transmission layer 29 made of an ultraviolet curable resin having a thickness of 0.1 mm was further laminated thereon.

The intermediate layer 251 was configured by laminating a dielectric layer 251b made of SiO ₂ having a thickness of 135 nm and dielectric layers 251a and c made of ZnS—SiO _{2 having} a thickness of 90 nm sandwiching the dielectric layer 251b.

  Further, a tracking guide groove having a pitch of 0.32 μm and a depth of 20 nm was formed on the substrate 20 (not shown).

  In this embodiment, laser light having a wavelength of 810 nm was used as initialization light, and laser light having a wavelength of 405 nm was used as recording / reproducing light.

  When the light transmittance of the intermediate layer 251 is measured, it can be set to a high value of about 85% for the recording / reproducing light, compared to about 40% for the initialization light. It was.

  Further, the absorptance with respect to the initialization light in the recording layer 23 was 1.5% (design value), which was a sufficiently low value to prevent the recording layer 23 from being deteriorated.

  With respect to the optical information recording medium according to this example, the phase change layer 27 was crystallized by irradiating the initialization light using an initialization apparatus having an optical head with NA = 0.55. Specifically, initialization was performed by moving the focused spot in the radial direction by 50 μm per rotation of the disk under the conditions of a linear velocity of 7.5 m / s and an irradiation laser power of 700 mW.

After initialization, the recording / reproducing light is irradiated using an optical head with NA = 0.85, and (1-7) modulated random data is recorded / reproduced under the conditions of a linear velocity of 4.92 m / s and a recording clock frequency of 132 MHz. As a result, a good error rate of 10 ⁻⁵ or less was obtained in the range of 13 mW recording power and 2.3 to 2.8 mW reproducing power.

  Therefore, in Example 2, the phase change layer 27 could be crystallized without the recording layer 23 being altered and being in a recorded state.

Example 3
Note that the transmittance for the initialization light can be further reduced by increasing the number of intermediate dielectric layers. FIG. 4 is a cross-sectional view schematically showing a configuration of an optical information recording medium according to the third embodiment. In Example 3, as shown in FIG. 4, the intermediate layer 252 is composed of five dielectric layers 252a to 252e. Other configurations are the same as those in FIG.

Specifically, the intermediate layer 252 is formed by alternately laminating dielectric layers 252a, c, and e made of ZnS-SiO ₂ having a thickness of 90 nm and dielectric layers 252b and d made of SiO ₂ having a thickness of 135 nm. Configured. The other thicknesses and compositions of the reflective layer 21, the dielectric layer 22, the recording layer 23, the phase change layer 27, the dielectric layer 28, and the light transmission layer 29 are the same as those in the second embodiment, and thus the description thereof is omitted.

  In this embodiment, laser light having a wavelength of 810 nm is used as the initialization light, and laser light having a wavelength of 405 nm is used as the recording / reproducing light.

  When the transmittance of the intermediate layer 252 of this example was measured, it was about 20% with respect to the initialization light, and could be set to a value equivalent to the single layer film of AgPdCu in Example 1. That is, even when the intermediate layer 252 of Example 3 was used, the same effects as those of Example 1 could be obtained.

Comparative Example 2
Information was recorded and reproduced using the optical information recording medium having the same configuration as in Example 2 without initializing the phase change layer 27. The linear velocity and recording clock frequency during recording were the same as those in Example 2. In this comparative example, since the phase change layer 27 was not initialized, the phase change layer 27 at the start of recording was in an amorphous state, and the recording power was 12.5 mW, which was slightly lower than that of Example 1. Although the reproduction power was changed variously, an error rate of 10 ⁻³ or less could not be obtained. As in the case of Comparative Example 1, this is considered to be caused by the fact that amorphous regions and crystal regions are mixed in the condensing spot of the recording / reproducing light and the S / N is lowered.

  Therefore, it was confirmed that by performing the initialization of the phase change layer 27, the error rate can be reduced and the S / N during reproduction can be improved.

Comparative Example 3
Further, as Comparative Example 3, in the optical information recording medium not provided with the above-described intermediate layer, the phase change layer was initialized and information was recorded and reproduced. FIG. 5 is a cross-sectional view schematically showing a configuration of an optical information recording medium according to Comparative Example 3. As shown in FIG. 5, this optical information recording medium has a substrate 50 made of polycarbonate having a thickness of 1.1 mm and a diameter of 120 mm, a reflective layer 51 made of AgPdCu having a thickness of 100 nm, and a thickness in order from the substrate 50 side. A dielectric layer 52 made of 30 nm SiN, a recording layer 53 made of Co ₃ O _{4 with} a thickness of 10 nm, a dielectric layer 54 made of ZnS—SiO _{2 with} a thickness of ₂₀ nm, and a phase made of Sb ₈₀ Te _{20 with} a thickness of 10 nm. A change layer 57 and a dielectric layer 58 made of ZnS—SiO _{2 having} a thickness of 55 nm were laminated by sputtering, and a light transmission layer 59 made of an ultraviolet curable resin having a thickness of 0.1 mm was further laminated thereon.

  In addition, a tracking guide groove having a pitch of 0.32 μm and a depth of 20 nm was formed on the substrate 50 (not shown).

  In this comparative example, laser light having a wavelength of 810 nm was used as initialization light, and laser light having a wavelength of 405 nm was used as recording / reproducing light.

  The thickness of each layer was set such that the reflectance change before and after recording was large when recording and reproducing information by irradiating the recording layer 53 with laser light of recording and reproducing light. In the optical information recording medium of this comparative example, the absorption rate of the recording layer 53 with respect to the initialization light was 8% (design value).

  Using the same initialization apparatus as in Example 1, the phase change layer 57 is initialized by moving the focused spot in the radial direction by 50 μm per rotation of the disk at a linear velocity of 7.5 m / s and irradiation laser power of 800 mW. went.

  Recording and playback of random data modulated with (1-7) modulation under conditions of linear velocity 4.92 m / s and recording clock frequency 132 MHz by irradiating recording / playback light using an optical head with NA = 0.85 after initialization. However, the recording layer 53 was altered during initialization, and recording itself could not be performed.

  That is, in the write-once super-resolution optical information recording medium, by providing the intermediate layer according to the present invention, information recording is possible after crystallization of the phase change layer, which is impossible when the intermediate layer is not provided. I was able to confirm that playback was possible.

Other Embodiments The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention. For example, laser light sources having other wavelengths that are available can be used for the laser light to be used. For example, laser light having a wavelength range of 380 to 430 nm can be used as recording / reproducing light. As the initialization light, laser light having a wavelength range of 680 to 900 nm can be used.

  The intermediate layer is not limited to AgPdCu, and other Ag alloys such as AgBi and AgPdTi can be used.

  When recording / reproducing light and initialization light in the above-mentioned wavelength range are used, the thickness of the intermediate layer made of an Ag alloy is 5 to 15 nm in order to balance the transmittance of recording / reproducing light and initialization light. It is desirable to be in the range.

  The intermediate layer is not limited to an Ag alloy, and other general metal materials such as an Al alloy and a Ni alloy can be used.

As the composition of the dielectric layer, ZnS—SiO ₂ and SiO ₂ may be interchanged.

The composition of the dielectric layer is not limited to ZnS—SiO 2, SiO 2, or SiN, and other dielectrics such as Ta 2 Ox can be used. Furthermore, the composition of the phase change layer is not limited to _Sb 80 _{Te 20,} it is possible to use _{GeSbTe, GeBiTe,} a Bi 2 Te 3, AgInSbTe or the like.

DESCRIPTION OF SYMBOLS 10 Substrate 11 Reflective layer 12 Dielectric layer 13 Recording layer 14 Dielectric layer 15 Intermediate layer 16 Dielectric layer 17 Phase change layer 18 Dielectric layer 19 Light transmission layer 20 Substrate 21 Reflective layer 22 Dielectric layer 23 Recording layer 25 Intermediate layer 27 Phase change layer 28 Dielectric layer 29 Light transmissive layer 50 Substrate 51 Reflective layer 52 Dielectric layer 53 Recording layer 54 Dielectric layer 57 Phase change layer 58 Dielectric layer 59 Light transmissive layer 60 Pit 61 Condensing spot 62 Aperture 70 Phase Change layer 71 Crystal region 72 Crystal region 73 Amorphous region 74 Recording layer 75 Recording mark 81 Melting portion 82 Focusing spot 91 Crystal region 251 Intermediate layer 251a Dielectric layer 251b Dielectric layer 251c Dielectric layer 252 Intermediate layer 252a Dielectric Layer 252b Dielectric layer 252c Dielectric layer 252d Dielectric layer 252e Dielectric layer

Claims (12)

A recording layer on which information is recorded by being irradiated with a first laser beam having a first wavelength;
A phase change layer formed between a light source of laser light and the recording layer and crystallized by irradiation with a second laser light having a second wavelength;
An optical information recording medium comprising at least an intermediate layer formed between the recording layer and the phase change layer and having a higher transmittance for the first laser light than a transmittance for the second laser light.   The optical information recording medium according to claim 1, wherein the intermediate layer is made of an alloy containing Ag.   The optical information recording medium according to claim 2, wherein the Ag alloy is AgPdCu.   4. The optical information recording medium according to claim 2, wherein the intermediate layer has a thickness of 5 nm to 15 nm.   The optical information recording medium according to claim 4, wherein a thickness of the intermediate layer is substantially 10 nm.   The optical information recording medium according to claim 1, wherein the intermediate layer is formed by alternately stacking first dielectric layers and second dielectric layers having different compositions. The optical information recording medium according to claim 6, wherein the first dielectric layer is made of ZnS—SiO ₂ , and the second dielectric layer is made of SiO ₂ . Assuming that the wavelength of the first laser beam is λ ₁ and the wavelength of the second laser beam is λ ₂ ,
8. The optical information recording medium according to claim _{1, wherein} 380 nm ≦ λ ₁ ≦ 430 nm and 680 nm ≦ λ ₂ ≦ 900 nm. 9. The optical information recording medium according to claim 8, wherein [lambda] ₁ is substantially 405 nm and [lambda] ₂ is substantially 810 nm. The refractive index for the second laser light in the first dielectric layer is n ₁ , and the refractive index for the second laser light in the second dielectric layer is n ₂ ,
The thickness of the first dielectric layer is λ ₂ / 4n ₁ , and the thickness of the second dielectric layer is λ ₂ / 4n ₂ . Optical information recording medium.   The information recording and reproduction are performed by irradiating the recording layer with the first laser beam after irradiating the laser beam with the second wavelength to crystallize the phase change layer. The optical information recording medium according to any one of 10. Forming a recording layer on which information is recorded by irradiation with a first laser beam having a first wavelength;
Forming a phase change layer that is crystallized by being irradiated with a second laser beam having a second wavelength, between the light source of the laser beam and the recording layer;
An optical information recording medium comprising at least a step of forming an intermediate layer between the recording layer and the phase change layer having a higher transmittance for the first laser light than that for the second laser light. Manufacturing method.

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